Laundry detergent compositions are typically made by a process that involves the step of spray-drying an aqueous slurry comprising anionic detersive surfactant to form a spray-dried powder. Typically, this spray-drying step is the rate determining step in the production of the laundry detergent powder. This is especially true for low-built formulations that have increased drying loads. With increasing global laundry detergent powder volume demand, many detergent manufacturers' spray-drying towers are running at, or very near, maximum capacity. In order to increase the capacity of their existing spray-drying facilities, detergent manufacturers have to either invest in additional or upgraded spray-drying equipment.
The inventors have found that the carefully controlling the viscosity of a shear-thinning slurry, and increasing its viscosity under specifically controlled shear conditions at a later stage in the spray-drying process, allows for an increase in the capacity of the process without the need for investment in additional spray-drying equipment.